This disclosure raises the curtain on the world of voltage pulse manipulation. There are a genre of primary elements placed to directly respond to changing physical states, exemplified by temperature, pressure, flow, and composition. These primary elements generate electrical voltage pulses at frequencies representative of variations in these physical states.
Narrowing attention to the frequency of these pulses, a predetermined range of their frequency can be analyzed and translated into signals which can manifest the instantaneous magnitude of the state and/or exert control over the change desired in that state. Perhaps more succinctly declared, if provided with a meaningful range of frequency, I can produce a meaningful translation of that range into a useful signal.
In the present art, voltage variations are simply referred to as pulses. The excursion of the voltage can vary in its magnitude and duration. In reaching its greatest magnitude, the pulse may have a first irregular growth rate from which it may decay at a second irregular rate. The irregularity of growth and decay rates reflects the subjective characteristic of the primary element generating the pulses. The first step in manipulating this train of pulses into useful form is to shape them into uniformity, particularly giving them a sharp actuating edge which may be either the leading, trailing, or both edges. Thus, the raw train of pulses discharged by many primary elements directly responsive to the physical state, are passed through a shaping circuit to provide a sharp edge to each pulse and thereby a precise measurement for the time between the pulses. This time, of course, is the frequency at which the pulses appear in the train.
Given a pulse train with meaningful variations in frequency, and given a circuit shaping the pulses to a uniform pattern, there is need for a circuit which will precisely sense the variation in the frequency of the pulses and ultimately produce a signal which is an interpretation of that frequency variation. The train of shaped pulses is fed as an input into a one-shot monostable multivibrator. The actuating edge of each input pulse triggers a corresponding output pulse from the one-shot. Each output pulse from the one-shot is adjusted to a predetermined duration corresponding to the maximum range of the frequency variation of the shaped input pulses. Thereafter, a decrease in the frequency of the primary pulse train to the one-shot within the predetermined range will create a time interval between the one-shot triggered output pulses. Perhaps more succinctly stated, the output of the one-shot becomes the time intervals between the triggered pulses of the one-shot, these time intervals representing frequencies within the predetermined range.
The intervals between the one-shot output pulses can then be placed in control of a third train of pulses of stable frequency. The pulses of the third train, with their stable frequency, are discharged during the variable intervals between the one-shot output pulses. A count of the number of third train pulses emitted between the one-shot pulses will represent the frequency of the first pulse train. There remains only the need to store and convert the third train pulses into a useful signal with which to manifest the frequency of the first train pulses and control the state that generates the first pulse train.